Microvalves are an integral part of many devices, particularly BioMEMS and “lab-on-a-chip” devices where minute quantities of fluids need to be manipulated. U.S. Patent application 20060118895 entitled “Electrostatic/electrostrictive Actuation of Elastomer Structures Using Compliant Electrodes” by Unger and assigned to Fluidigm Corporation describes implementation of such a microvalve design. In one design, Fluidigm describes a fluid flow through a main conduit. Adjustments of pressure in a control conduit running perpendicular to the main conduit bows an elastic wall separating the two conduits thereby controlling fluid flow through the main conduit without fluid mixing.
One problem with the Fluidigm design is the need for an array of separate external pneumatic actuation/pressure control valves. In order to control each microvalve, each microvalve requires a corresponding external actuation/pressure control valve. Implementing an array of such external actuation/pressure controllers adds significantly to the cost and bulk of the Fluidigm microvalves.
An alternate Fluidigm design, utilizes electrostatic forces to directly move a membrane between two positions and thereby close a microvalve. However, using this design, electrostatic forces are typically only sufficient to switch a microvalve in a low pressure system. At higher pressures, the electrostatic forces are insufficient to directly manipulate higher pressure fluid flow.
Thus a less bulky, more inexpensive microvalve that is capable of controlling higher fluid pressures is needed.